Sliding-vane rotary fluid displacement machine



Nov. 10, 1970 L, KRAMER 3,539,281

SLIDING-VANE ROTARY FLUID DISPLACEMENT MACHINE) Filed July 22, 1968INVENTOR LEO KRAMER %M mwum- ATTORNEY United States Patent Olfice3,539,281 Patented Nov. 10, 1970 US. Cl. 418-125 13 Claims ABSTRACT OFTHE DISCLOSURE A sliding-vane rotary fluid displacement machine whichcan be utilized as a motor, a pump or a compressor and includes a rotorcarrying a plurality of sliding vanes which are positively moved outwardby an eccentric as the rotor rotates. The rotor and vanes are surroundedby a cylinder which is supported on the tips of the vanes and rotateswith the rotor about the axis of the eccentric.

BACKGROUND OF THE INVENTION This invention relates to the art ofsliding-vane type rotary fluid displacement machines and particularly tovane type gas-operated motors.

Conventional sliding-vane rotary gas motors have the undesirablecharacteristics of an inability to operate satisfactorily at low speeds,say 100 rpm. Generally, this undesirable characteristic is caused by thefailure of the vanes to be thrust outward against the motor bore. Manyattempts have been made to hold the vanes out at low speeds butgenerally such attempts have reduced the motors ability to operate athigh speeds and also greatly increased the normal wear of the vanes. Inaddition, although sliding-vane type motors can operate at relativelyhigh speeds, their maximum speeds are greatly limited by the relativelyhigh friction caused by the rubbing speed of the vane tips on the motorbore.

SUMMARY OF THE INVENTION The principal object of this invention is toprovide a sliding-vane rotary fluid displacement machine which willoperate satisfactory at both high and low speeds and will markedlydecrease the wear of the vanes as compared to conventional machines ofthis type.

Other important objects of this invention are: to provide a sliding-vanerotary machine which has its vanes held outward against the surroundingrotor bore at all times; to provide a sliding-vane rotary machine havinga cylinder that rotates with the rotor; to provide a slidingvane rotarymachine having a rotary cylinder that is supported on the tips of therotor vanes; to provide a sliding-vane rotary machine wherein therelative sliding movement or rubbing speed between the vane tips and therotor bore is less than one tenth the corresponding relative movement inconventional sliding-vane machines; to provide a sliding-vane rotarymachine having a much higher terminal speed as compared to conventionalmachines; and to provide a sliding-vane rotary machine in which metalvanes can be used practically.

The foregoing objects of this invention are generally attained in amachine including a rotor; a cylinder eccentrically surrounding therotor and forming a fluid displacement space between the cylinder andthe rotor, a set of sliding vanes carried by the rotor with their outerends or tips engaging the interior of the cylinder, and a fixedeccentric holding the vanes outwardly to support the cylinder so that itrotates with the rotor about the eccentric axis of the eccentric. Thisconstruction greatly reduces the rubbing speed of the vane tips thusgreatly reducing wear of the vanes and allowing the machine to operateat higher speed. The reduction in friction also allows the practical useof vanes made of a variety of materials, such as metal, which are easierto manufac ture, more economical, have better frictional properties,have more strength, etc. Finally, when used as a motor, it will operateat very low speeds as well as very high speeds.

BRIEF DRESCRIPTION OF DRAWINGS The invention is described in connectionwith the accompanying drawing wherein:

FIG. 1 is a cross-section of a sliding-vane rotary motor taken on line11 of FIG. 2 and illustrating applicants invention;

FIG. 2 is an axial section taken on line 22 of FIG. 1;

FIGS. 3 to 5 are schematic views showing sequential relative positionsof the rotor and cylinder in the motor; and

FIG. 6 is a schematic sectional view of a vane illustrating itscorrespondence to a portion of a cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The air motor 1 shown in thedrawing includes a casing 2 composed of a body 3 and a pair of endplates 4 and 5. The end plates 4 and 5 are attached to the casing body 3by several longitudinal bolts (not shown) passing through each of thecasing parts.

The casing body 3 includes a cylindrical bore 6 ex tending between theend plates 4 and 5 and having the several moving components of themotor 1. A cylindrical rotor 7 is mounted eccentrically in the bore 6.One end of the rotor 7 includes a driving shaft 8 extending through theend wall 4 and rotatably mounted in a bearing 9. The other end of therotor 7 is rotatably mounted on a bearing 10 supported on a fixedspindle 11 attached in the end wall 5. The rotor 7 is made in two'parts14 and 15 to aid in assembly of the motor. The rotor part 14 iscup-shaped and is integral with the drive shaft 8. The rotor part 15 isan end cap which closes the open end of the rotor part 14.

The rotor 7 is surrounded by a hollow cylinder 16 which fits in thecasing bore 6 with a substantial amount of clearance therebetween. Boththe rotor 7 and the cylinder 16 are sealingly engaged by the end walls 4and 5 of the casing to substantially prevent leakage while allowingthese elements to rotate freely with small friction losses. The cylinder16 is eccentrically spaced from the rotor 7 to form a crescent shapedfluid displace ment space 17 between the rotor 7 and the cylinder 16.

The rotor 7 carries a plurality of radially extending sliding vanes 18spaced around its periphery and having their tips or outer edgesengaging the interior of the cylinder 16. The inner edges of the vanes18 ride on a bearing 19 rotating on a fixed eccentric 20 which isadjusted to cause the cylinder 16 to rotate in the casing bore 6 andabout the axis of the eccentric 20. The eccentric 20 is supported on theinboard end of the spindle 11. In essence, the cylinder 16 is carried onthe outer tips if the sliding vanes .18 and the vanes 18 are carried onthe eccentric 20, as a result, causing the cylinder to rotate around theaxis of the eccentric.

The inner end of the eccentric 20 and spindle 11 is further supported ina bearing 22 mounted in the rotor part 14, thus providing the spindlewith support at both ends and contributing additional support to therotor 7.

Fluid is fed into and exhausted from the crescentshaped fluiddisplacement space 17 through ports located in the end wall 5 of thecasing 2. The casing body 3 includes an inlet 23 and an outlet 24. Theinlet 23 extends along an inlet passage 25 formed as a groove in thebore 6 to an inlet port 27, which is also formed as an acruate grooveformed in the inside face of the end wall 5. The outlet 25 also isconnected by an outlet passage 28 to an exhaust port 29 formed in theface of the end wall 5.

The compressed air or other fluid is fed through the inlet port 27 intothe fluid displacement space 17, expands and drives the vanes 18, rotor7 and cylinder 16 in a clockwise direction, as shown in FIGS. 1 and 3 to5. When the motor rotates sufliciently, the compressed fluid isexhausted through the exhaust port 29 and out of the outlet 25. It isbelieved that the general principles of the operation of a sliding-vanerotary motor is well known to those skilled in the art and that theforegoing is suflicient to understand the rotation of the motor 1.

In order to prevent leakage between the inlet and exhaust ports 27 and29, a plurality of seals 31 are placed between the bore 6 and theexterior of the cylinder 16. Each seal 31 is located in a longitudinalgroove in the wall of the bore 6 and extends the length of the cylinder16. Light springs 32 are positioned behind each seal 31 near its ends tourge it inwardly against the cylinder 16. The placement of the seal 31can be adjusted to substantially balance the pressures acting on theexterior and interior of the cylinder 16 so that the eccentric bearing19 does not carry a large unbalanced load. In other words, the seal 31are located so that the cylinder 16 substantially floats in the bore 6.

As the rotor 7 and its vanes 18 rotate, the tips of the vanes 18 supportthe cylinder 16 and carry it with the rotor 7 so that the cylinder 16rotates at about the same speed as the rotor. The exact relationshipbetween the speeds of the rotor 7 and cylinder 16 will vary due to themotor speed, the friction between the vane tips 18 and the cylinder '16,and the unbalanced load on the cylinder. Generally, it has been foundthat the cylinder 16 and rotor 7 will rotate at equal rpm. at low motorspeeds and that the cylinder 16 will rotate at slightly less r.p.m. thanthe rotor 7 at high speeds. However, the foregoing does not always holdtrue. The relative speed between the cylinder 16 and rotor 7 is afunction of the frictional forces acting on these two elements,generally the rubbing friction of the vanes on the cylinder 16, andthese frictional forces vary under different conditions. At times, thecylinder 16 rotates slightly faster than the rotor 7 at high motorspeeds.

FIGS. 3 to illustrate three sequential positions of the rotor 7, vanes18 and cylinder 16 when the cylinder 16 is traveling at a slightlyslower speed than the rotor 7. A spot 34 is placed on the cylinder 16 ineach of these views to illustrate the relative positions of the cylinder16 as the motor parts rotate.

I have found that this motor 'Will rotate at very low speeds, say 100rpm, and also rotate at about twice the maximum speeds of a conventionalsliding-vane motor having similar dimesions. In addition, the rubbingtip speeds of the vanes 18 on the cylinder 16 is reduced about 95percent of that in a conventional motor, which will provide much longerWear life of the vanes and will enable the use of other materials, suchas metal, which are not practical in conventional sliding-vane motors.

In order for the vanes 18 to support the cylinder 16 firmly, withoutwobbling of the cylinder, each vane 18 comprises a diametrical portionof an imaginary cylindrical roller. This construction of the vane 13 isshown in FIG. 6. The roller 36 is shown in dotted lines while the vane\18 is shown in solid lines. The axes of the roller 36 and the vane .18are the same and the edge 37 of the vane 18 are portions of thecircumference of the roller 36. By having cylindrical edges 37, thevanes 18 can move slightly out of a diametrical relationship with thecylinder 16 as they must do as the rotor 7 rotates, without allowing thecylinder 16 to wobble.

Although the decribed embodiment is referred to as a motor, it could bea compressor simply by driving the 4 drives shaft 8. The concepts setforth could also be used in making a pump.

I claim:

1. A sliding-vane rotary fluid displacement machine comprising:

a casing;

a rotor mounted in said casing to rotate about a given axis and carryingat least three vanes slidably projecting from its circumference atangularly spaced locations about said axis;

a cylinder freely mounted in said casing surrounding said rotor andhaving an axis eccentric to said rotor axis to provide a fluiddisplacement space between said rotor and the interior of said cylinder;and

means positively holding said vanes outward against the interior of saidcylinder and simultaneously supporting and forcing said cylinder torotate about said eccentric axis while said rotor rotates about itsaxis.

2. The machine of claim 1 wherein: said vanes have arcuate edgesengaging said cylinder and said means.

3. The machine of claim 2 wherein: each of said vanes has across-section which corresponds to a portion of a cylindricalcross-section.

4. The machine of claim 1 wherein:

said casing includes a pair of end walls engaging the ends of said rotorand cylinder and sealing said fluid displacement space; and

at least one of said end walls contains a fluid port for introducingfluid into said fluid displacement space.

5. The machine of claim 4 wherein: at least one of said end wallscontains a fluid port for exhausting fluid pressure from said fluiddisplacement space.

6. The machine of claim 5 wherein: said casing includes sealing meansengaging the outer periphery of said cylinder to separate said fluidports.

7. The machine of claim 1 wherein: said means is a fixed eccentricengaging the inner edges of said vanes.

8. The machine of claim 7 wherein: said eccentric includes a bearingrotating around an eccentric core and engaging the inner edges of saidvanes.

9. The machine of claim 7 wherein:

said rotor includes a rotatable shaft projecting from one end of saidcasing and is rotatively supported on a fixed spindle mounted at theother end of said casing; and

said eccentric is supported on said fixed spindle.

16. The machine of claim 7 wherein: said rotor is rotatably supported onsaid fixed spindle at two separate points located on the opposite sidesof said fixed eccentric.

11. A rotary fluid displacement machine comprising:

a rotor;

a cylinder eccentrically surrounding the rotor, mounted free to rotatewith said rotor and forming a fluid displacement space between saidcylinder and rotor;

a pair of opposite end plates closing the ends of said displacementspace and sealingly engaging the ends of said cylinder and rotor;

21 set of vanes slidably carried by said rotor and having their outerends extending outwardly from the circumference of said rotor andengaging the interior of said cylinder; and

a fixed eccentric cam holding the vanes outwardly to support saidcylinder so that it rotates with said rotor about an axis eccentric tothe rotor axis.

12. The machine of claim 11 wherein: said eccentric includes a bearingsurface engaging said vanes to reduce wear.

13. A rotary fluid displacement machine comprising:

a rotor;

a casing having a bore eccentrically surrounding the rotor;

21 pair of opposite end plates closing the ends of said bore andseulingly engaging the ends of said rotor;

a set of vanes slidably carried by said rotor and having their outerends engaging the interior of said bore; and

a fixed eccentric cam holding the vanes outward against said bore tocause the outer tips of said vanes to continuously engage said boreduring the rotation of said rotor.

References Cited UNITED STATES PATENTS 6 Bergen. Humphreys. Clark103-136 X Eickemeyer 91-70 X Grimm 91-70 X GoodWyn 91-121 X U.S. Cl.X.R.

